The esophagus ... not just for food anymore?

Abstract

Background Survival of patients with acute lung injury or the acute respiratory distress syndrome (ARDS) has been improved by ventilation with small tidal volumes and the use of positive end-expiratory pressure (PEEP); the optimal level of PEEP has been difficult to determine. In this pilot study, we estimated transpulmonary pressure with the use of esophageal balloon catheters. We reasoned that the use of pleural-pressure measurements, despite the technical limitations to the accuracy of such measurements, would enable us to find a PEEP value that could maintain oxygenation while preventing lung injury due to repeated alveolar collapse or overdistention. Methods Objective To evaluate the effectiveness of using an esophageal balloon catheter to measure pleural pressure and guide PEEP titration to achieve normal physiologic parameters in individual patients. Design Single center, randomized-controlled pilot trial. Setting: Medical and surgical ICUs at Beth Israel Deaconess Medical Center. Subjects 61 patients with acute lung injury or ARDS as defined by the American-European Consensus Conference definition. Intervention Patients with acute lung injury or ARDS were randomly assigned to undergo mechanical ventilation with PEEP adjusted according to measurements of esophageal pressure (the esophageal-pressure-guided group) or according to the Acute Respiratory Distress Syndrome Network standard-of-care recommendations (the control group). Outcomes The primary end point was improvement in oxygenation at 72 hours after randomization. Secondary end points included indexes of lung mechanics and gas exchange, number of ventilator free days, length of ICU stay, and death at 28 days and 180 days. Results The study reached its stopping criterion and was terminated after 61 patients had been enrolled. The ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen at 72 hours was 88 mmHg higher in the esophageal-pressure-guided group than in the control group (95% confidence interval, 78.1 to 98.3; P = 0.002). This effect was persistent over the entire follow-up time (at 24, 48, and 72 hours; P = 0.001 by repeated-measures analysis of variance). Respiratory-system compliance was also significantly better at 24, 48, and 72 hours in the esophageal-pressure-guided group (P = 0.01 by repeated-measures analysis of variance). Conclusions As compared with the current standard of care, a ventilator strategy using esophageal pressures to estimate the transpulmonary pressure significantly improves oxygenation and compliance. Multicenter clinical trials are needed to determine whether this approach should be widely adopted. (ClinicalTrials.gov number, NCT00127491.)